Recycled oyster shells are being used by a scientist and traditional owners to try and restore the biodiversity and water quality of Moreton Bay in in South East Queensland.
And first trial results are showing signs the project is working.
Oysters are known as the ‘kidneys of the coast’ due to their natural filtration properties. They improve water clarity by drawing in particles and sending them to the seafloor.
Once grown, each oyster can filter up to 100 litres of water a day.
Local oyster beds in Moreton Bay became unviable 20 years ago, so instead, in the town of Ningi, shell waste from Australia’s huge appetite for oysters is being recycled.
Oyster recycling for artificial reefs in Pumicestone Passage at Bribie Island. Source: Stefan Armbruster
The discarded shells from New South Wales, Tasmanian and South Australian oysters are cleaned and packed into four-by-four metre wire cages, then go back into the sea as artificial reefs.
It is a project combining traditional knowledge and modern science that could one day dramatically improve the health of Australia’s coastal waters.
Oystering was once of Queensland’s most important colonial-era industries. Moreton Bay oysters fed the demand from Sydneysiders and reefs were dredged for lime used to build early Brisbane.
But devastating floods 120 years ago after mass land clearing in the region smothered the bay’s over-exploited reefs with mud, eventually leading to habitat extinction.
Several large scale projects are underway around Australia but this three-year trial is community driven.
Source: Supplied
Last year, artificial oyster reefs made of recycled shells were sunk in Pumicestone Passage, a narrow waterway between the Queensland mainland and Bribie Island, to see if it was possible to re-establish them in coastal waters. Almost 12 months on, there is some evidence it is working.
Underwater footage shows once barren and silted mudflats now have new life. Three meters down, the artificial reef is teaming with fish and baby oysters have started growing on the recycled shells.
Oyster spat grows on recycled oyster shells after almost a year in the water on an artificial reef. Source: Stefan Armbruster
